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Peter Dowben Publications Research Papers in Physics and Astronomy

July 2003

Boron-Carbide and Boron Rich Rhobohedral Based Transistors and Tunnel Diodes

Peter A. Dowben University of Nebraska-Lincoln, [email protected]

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Dowben, Peter A., "Boron-Carbide and Boron Rich Rhobohedral Based Transistors and Tunnel Diodes" (2003). Peter Dowben Publications. 74. https://digitalcommons.unl.edu/physicsdowben/74

This Article is brought to you for free and open access by the Research Papers in Physics and Astronomy at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Peter Dowben Publications by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. (12) United States Patent (10) Patent NO.: US 6,600,177 B2 Dowben (45) Date of Patent: Jul. 29,2003

(54) BORON-CARBIDE AND BORON RICH (56) References Cited RHOMBOHEDRAL BASED TRANSISTORS U.S. PATENT DOCUMENTS AND TUNNEL DIODES 6,025,611 A * 212000 Dowben ...... 2571183 (75) Inventor: Peter A. Dowben, Crete, NE (US) * cited by examiner (73) Assignee: Board of Regents, University of Primary Examiner4eorge Fourson Nebraska-Lincoln, Lincoln, NE (US) Assistant Examiner-Thanh V Pham (74) Attorney, Agent, or FirmSuiter West PC LLO ( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 (57) ABSTRACT U.S.C. 154(b) by 0 days. The present invention relates to the fabrication of a boron carbideboron semiconductor devices. The results suggest (21) Appl. No.: 091991,768 that with respect to the approximately 2 eV band gap pure boron material, 0.9 eV band gap boron carbide (B5C) acts as (22) Filed: Nov. 16, 2001 a p-type material. Both boron and boron carbide (B5C) thin (65) Prior Publication Data films were fabricated from single source borane cage mol- ecules using plasma enhanced chemical vapor deposition US 200210045300 A1 Apr. 18, 2002 (PECVD). Epitaxial growth does not appear to be a require- Related U.S. Application Data ment. We have doped boron carbide grown by plasma enhanced chemical vapor deposition. The source gas closo- 1,2-dicarbadecaboran' (orthbcarborane) was used to grow (60) Division of application No, 091465,044, filed on Dee 16, 1999, now Pat. No. 6,440,786, which is a continuation-in- the boron carbide while nickelocene (Ni(CsH5)2) was used vart of avvlication No. 091933,362, filed on Sev. 19, 1997, to introduce nickel into the nrowinn film. The dovinn of , , . , u u . u now P~~:NO.6,025,611. nickel transformed a B5C material p-type relative to lightly (60) Provisional application No. 601026,972, filed on S~P.20, doped n-type silicon to an n-type material, Both p-n hetero- 1996. iunction diodes and n-p heteroiunction diodes with n- and p-type Si [1,1,1] respectively. With sufficient partial pres- (51) Int. CL7 ...... HOlL 2110328 sures of nickelocene in the plasma reactor diodes with characteristic tunnel diode behavior can be successfully (52) U.S. C1...... 2571183; 2571200; 2571201 fabricated,

(58) Field of Search ...... 2571183, 20CL201 15 Claims, 8 Drawing Sheets "" "-@ VDS (-1 Source Drain U.S. Patent Jul. 29,2003 Sheet 1 of 8

Applied Bias (V) FIG. la

Applied Bias (v:) FIG. lb U.S. Patent Jul. 29,2003 Sheet 2 of 8 US 6,600,177 B2

Source Drain

FIG. 2a

0.5 -

-0 -

-3.5 - tlrlrlflll~~,~~~~~l~~t - -5.5 -5.0 - 4.0 -3.0 - 2.0 -1 -0 0.0 0.5 VDS Drain Voltage (V) FIG. 2b U.S. Patent Jul. 29,2003 Sheet 3 of 8 U.S. Patent Jul. 29,2003 Sheet 4 of 8 U.S. Patent Jul. 29,2003 Sheet 5 of 8 U.S. Patent Jul. 29,2003 Sheet 6 of 8 U.S. Patent Jul. 29,2003 Sheet 7 of 8

Applied Bias (V) FIG. 5a

Applied Bias (v) FIG. 56 U.S. Patent Jul. 29,2003 Sheet 8 of 8

FIG. 6 US 6,600,177 B2 1 2 BORON-CARBIDE AND BORON RICH Recent successes in construction of boron carbideln-Si RHOMBOHEDRAL BASED TRANSISTORS [1,1,1] heterojunction diodes [5,6] have demonstrated that AND TUNNEL DIODES boron carbidelsi [1,1,1] heterojunction diodes can be fab- ricated from closo-1,2-dicarbadodecaborane(C2BloH12; RELATED APPLICATIONS s orthocarborane) by using synchrotron radiation induced This application is a divisional of U.S. patent application chemical vapor deposition (SR-CVD) [5, 61, and plasma Ser. No. 091465,044, filed Dec. 16, 1999, now U.S. Pat. No. enhanced (PECVD) L2, 3, 5-71. 6,440,786, which is a continuation in part of U,S, patent Pure boron films also had been deposited on silicon from application Ser. No. 091933,362, now U.S. Pat. No. 6,025, nidO-decabOrane (B~oH~,;decabOrane) using SR-CVD 611 filed Sep. 19, 1997, which claims priority under 35 10 [8, 91. Boron carbidein-Si [1,1,1] heterojunction devices U.S.C. §119(e) to provisional application Ser. No. 601026, fabricated carbide nidO- 972, filed Sep. 20, 1996. Each of said applications is pentaborane and using PECVD is and incorporated herein by reference in its entirety. described in U.S. Pat. No. 5,468,978, hereby incorporated by reference in its entirety. GOVERNMENT RIGHTS IS SUMMARY OF THE INVENTION This work resulted in part from research conducted under U.S. Air Force grant AF~SRF49620-94-1-0433. The gov- It is an object of the present invention to provide boron1 ernment has certain rights in this invention. boron carbide and doped boron carbide semiconductor devices and techniquesto fabricate same. BACKGROUND OF THE INVENTION 20 It is another obiect of the vresent invention to vrovide a The present invention relates to a process for the depo- semiconductor device suited for use in high temperature, sition of boron carbide semiconductor material, and also to corrosive, mechanically abrasive, or radioactive environ- semiconductor devices formed by deposition of a boron ments. carbide film. The invention is more particularly directed to 25 ~~~~h~~ object of the present invention is to provide a technique for creating a layer of boron carbide with a boron carbide semiconductor devices and fabrication tech- boron-to-carbon ratio of about 5. The invention is also niques which do not require a silicon interface, particularly directed to semiconductor devices produced by Yet another object of the present invention is to provide this technique. boron carbide semiconductor devices and fabrication tech- Boron and boron carbide devices have been sought since 30 niques to fabricate same which do not depend on epitaxial 1959 [I] but only recently has the fabrication of these growth or crystallite size, devices been realized [2, 31. Such devices would have Still another object of the present invention is to provide applicability in a wide number of harsh conditions. For example, they should be resistant to corrosive, high doped boron carbide semiconductor devices and fabrication techniques for making same. In one embodiment, the doped temperature, and mechanically abrasive environments. 35 boron carbide appears as n-type relative to an n-type silicon Because of the large neutron capture cross-section, these substrate. materials could be used in devices in radioactive environ- ments as well [4]. The objects of the present invention are provided by the Techniques are known for forming boron-rich carbides, boronlboron carbide heterojunction devices and the doped These techniques may employ alkanes and heavy boron cage 40 boron carbidelsilicon semiconductor devices and fabrication molecules to deposit boron carbide thin films. Plasma- as herein. enhanced chemical vapor deposition (PECVD) can be The fabrication of several working boronlboron carbide employed to fabricate boron carbide films without resort to semiconductor devices is described herein. In an effort to high temperatures or high pressures, ~h~~~ technique typi- fabricate a more sophisticated device, a transistor was made cally employ a halide of boron, e.g., BCl,, BBr, or Bl,. Most 45 in a PECVD system. A diode was made directly on an recently boranes, such as nido-decaborane and nido- aluminum substrate to demonstrate that a silicon interface is pentaborane have gained interest, because these compoun~s not essential for fabrication of a boron carbide device. The are safe and stable, yet produce a vapor pressure of several Use of plasma enhanced chemical vapor deposition Torr at room temperature. However, until very recently, only (PECVD) provides a means for fabricating boron and boron low-resistivity boron carbide materials could be produced, so carbide thin films successfully in a high resistivity form [2, i.e., materials with resistivities on the order of about ten 31 The Present invention addresses some of the issues ohm-cm at room temperature, Boron carbide material of this associated with making devices of increasing complexity type has an extremely low band gap, and is not suited as a from boron carbide. semiconductor material. The aluminum substrates were polycrystalline, and the At the same time, boron carbide has become an attractive ss silicon substrates were [1,1,1], n-type. Both were chemically material because of its inherent hardness and durability, etched and cleaned prior to insertion in vacuo and set on the Boron carbide, like other boron-containing materials, has lower electrode. The substrates were further cleaned by Ar' been considered for high temperature electronic devices b~mbardmentat 300 mTOrrr, 40 W and annealed at 400' C. because it retains its useful characteristics at elevated tem- in the vacuum system. Deposition was carried out in a peratures. For example, boron carbide is known to have a 60 custom designed parallel plate 13.56 MHz radio-frequency melting temperature of 2350" C., a strength of 50 ksi, a plasma enhanced chemical vapor deposition (PECVD) reac- hardness of 2800 kgimm2, and a thermal conductivity of tor described previously [3,7]. Asuitable plasma chamber in 0.22 cal/cm/sec/O C,/cm, Diamond and silicon carbide have which this technique can be carried out is shown and been investigated because of their good thermal and described in U.S. Pat. NO. 4,957,773, hereby incorporated mechanical characteristics, and because of their wide band 65 by reference in its entirety. gaps. However, these materials have not yet proven cost The above, and many other objects and advantages of the effective. present invention will become apparent from the ensuing US 6,600,177 B2 3 4 detailed description of the invention, to be read in conjunc- The diode I-V characteristics of a B5C~oronialuminum tion with the accompanying drawings. structure are seen in FIG. la. Although not shown here, a boronialuminum structure exhibits an ohmic characteristic, BRIEF DESCRIPTION OF THE DRAWINGS which leads to the conclusion that a iunction exists between FIG. la is a graph of diode I-V characteristics of a boron 5 the B5C and boron with the B5C acting as the &'-type carbide~oronialuminumdevice according to the present material. The I-V diode characteristics of a B5Cboron/n- invention with a schematic cross sectional view of the diode type silicon structure are seen in FIG. lb. In this case the structure and wire connections for characteristics shown in boronin-type silicon structure, which is not shown, exhibits the inset. a diode characteristic with the boron acting as a p-layer with 10 respect to the n-type silicon. This result, combined with FIG. lb is a graph of diode I-V characteristics of a boron results of FIG. and the boronialuminum structure indicate carbideboronin-Si [1,1,11 device according to the present la the B5Cboron/n-type silicon structure consists of two invention with a schematic cross-sectional view of the diode structure and electrical wire connections for characteristics diodes in series oriented in the same direction. This is borne out by the observed diode curve in FIG. lb. Furthermore, shown in the inset. IS neither structure exhibits the classical exponential diode FIG. 2a shows the schematic cross-sectional geometry of behavior in the fornard direction, This type of behavior is fabricated boron carbide junction field-effect transistor similar to the previously reported boron carbidein-type Si LJFET1 according to the present invention. The schematic [1,1,1] heterojunction [2, 31, It has been demonstrated that also illustrates electrical wire connections as well as polari- boron carbide thin film on n-type Si [1,1,1~ heterojunction ties of each applied biases. 20 diodes are insensitive to the morphology of the film [6]. The FIG. 2b shows transistor characteristics of ID (drain semiconductor properties of the material do not appear to current) vs. VDS for the device shown in FIG. 2a. Gate depend upon crystallite size and the extent of long range voltage, VG, was applied from 0 V to 10 V by the step of 2 order, and similar material can be grown on other substrates V. such as silver, Si [1,1,1], and titanium. FIG. 3 shows the transistor characteristics of I, (gate 25 ~h,fabricated boron car~i~e~oron~si~iconmultilayer current) vs. VDS for the device shown in FIG. 2a. Note that, device can be employed as a junction field effect transistor relative to FIG. 2, the currents are small. (JFET). FIG. 2a shows the schematic diagram of the mea- FIG. 4a shows the schematic cross-sectional geometry of surement circuit, while FIG. 2b shows the drain current vs. a boron carbidein-Si [1,1,1] heterojunction and a graph of drain voltage, with the source at ground, as a function of the diode I-V characteristics for the device shown. 30 gate voltage. Based on the characteristics of FIG. lb, the FIG. 4b shows the schematic cross-sectional geometry of gate is biased positive, while the drain is swept through the high nickel doped boron carbidein-Si [1,1,1] heterojunc- negative voltages, each with respect to the grounded source. tion according to the present invention and a graph of diode As the gate voltage is increased, the magnitude of the drain I-V characteristics for the device shown. current decreases for any given value of drain voltage, which FIG, 4c shows the schematic cross-sectiona~geometry of 35 is the expected behavior for a JFET. It should be pointed out the low nickel doped boron carbide/n-Si [1,1,1] heterojunc- that the device does not saturate, nor does it completely cut tion according to the present invention and a graph of diode off. This is probably a result of the fact that this is a single I-V characteristics for the device. junction device, and the junction is relatively far removed FIG. 5a shows a graph of I-V diode characteristics a 40 from the source and drain region. nickel doped boron carbide heterojunction diode, with low FIG. 3 is the gate current vs. drain voltage as a function nickel doping concentrations, according to the present of gate voltage. When combined with FIG. 2b, this clearly invention. indicates the leakage current is less than 10% of the drain FIG. 5b shows a graph of I-V diode characteristics a current. nickel doped boron carbide heterojunction diode, with high 45 Diodes fabricatedpm bo~oncarbide with $rystallites of nickel doping concentrations, according to the present different sizes (30 A, 100 A and 24@340 A) have been invention. compared [6]. While the ideality factors of these diodes do FIG, 6 is a graph of diode 1-v characteristics of a boron differ, similar rectifying diodes were fabricated [6] to the rich semicon~uctorhomojunction diode according to the ones shown in this work. It is believed that this insensitivity present invention with the schematic cross-sect~ona~geom- so to crystal grain size and the clear evidence that devices can etry of the diode shown in the inset. be fabricated on very different substrates provides some evidence that epitaxial growth is not a determining issue in DETAILED DESCRIPTION OF THE the fabrication of devices made with this microcrystalline or INVENTION polycrystalline semiconductor material. using CVD sources, boron carbideboron multilayers 55 The fabrication of heterojunction devices from plasma were deposited on aluminum and silicon. FIG. la shows the enhanced [11-141 and synchrotron radiation 151 chemi- schematic cross-sectional view of the fabricated multilayer cal vapor deposition is possible from decom~ositionof devices, ~~~~b~~~~~was used to form a pure boron film on cluster borane molecules. In fact, not only have diodes been the substrates. Boron carbide (B5C) films were then depos- fabricated, but a field effect transistor as well [131. ited on the pure boron layer from orthocarborane. The purity 60 Nonetheless, no intentional doping of this material grown by of the orthocarborane and decaborane was determined by plasma enhanced chemical vapor deposition (PECVD) has infrared (IR), nuclear magnetic resonance (NMR) and mass been attempted success full^ prior to this work. spectral measurements (purity 98%) and compared with Attempts to dope films of the molecular icosahedra closo- literature values [lo]. Less than 1% of the metacarborane 1,2-dicarbadodecaborane (orthocarborane) have not been and paracarborane isomers were found to be present. The 65 uniformly successful. Such molecular films can be doped decaborane was sublimed to separate the source material with sodium [16, 171, but not the more common dopant from cellite (a stabilizer) and other impurities [lo]. mercury [16]. Since the suitability of orthocarborane US 6,600,177 B2 5 6 (C2BloH12) for the chemical vapor deposition of a boron on p-type silicon, again by including nickelocene with the carbide film suitable for making devices has been estab- orthocarborane as an additional source gas, as seen in FIG. lished [13, 151, these results suggest that doping of this 5a. material may be a complex process. With the higher nickel doping levels, a negative differ- Nonetheless, nickel is a very promising dopant for the 5 ential resistance or a valley current in the effective forward boron rich solids. Amolecular nickel carborane complex has bias direction for diodes formed on both n-type silicon and been synthesized by inorganic chemists [18] and the inclu- p-type silicon substrates is apparent as seen in FIGS. 4c and sion of nickel in other boron rich solids is well established. 5b. This behavior is characteristic of a tunnel diode [24]. Nickel is a common component in the boron carbide super- This is consistent with degenerative doping of a pinned state conductors [19] and the reactions of nickel with boron 10 relative to the conduction band edge. phosphide have been investigated [20,21]. Nickelocene, Ni States pinned to one band edge have been proposed for (C5H5), has been shown to be a suitable source compound boron carbide [22] and have been identified pinned to for the deposition of nickel containing thin films [22]. conduction band edge [25, 261. The hump in the current Nickelocene is volatile and far less toxic than nickel occurs with at a larger bias voltage for the tunnel diodes carbonyl, though a number of other nickel containing orga- 15 fabricated on the p-type silicon. This consistent with the nometallic compounds may be suitable [23]. Since both boron carbide thin film acting as an n-type layer and the orthocarborane and nickelocene are easily sublimed from formation of heterojunction n-p diodes. See also [27]. the solid, introduction of suitable mixtures into the plasma FIG, 6 shows the 1-v characteristics and corresponding reactor can be readily accomplished. schematic diagram of a trilayer diode that has been fabri- The p-n and n-p heterojunctions were formed by depos- 20 cated from a PECVD nickel doped B5C layer deposited on iting boron carbide thin films on n-type and p-type Si [1,1,1] an undoped PECVD B5C layer, with a semiconductor homo- substrates respectively, doped to 7~10~~/cm~,following junction formed therebetween. The undoped PECVD B5C procedures described in detail elsewhere [ll, 121. The Si layer was deposited on a PECVD rhomboherdal boron layer [1,1,1] substrates surfaces were prepared by Ar' ion sput- placed on an aluminum substrate. Other dopants that may be tering in the plasma reactor. Deposition of the films was 25 employed include, for example, phosphorous, chromium, performed in a custom designed parallel plate 13.56 MHz manganese, iron, cobalt, and ruthenium. radio-frequency PECVD reactor used in previous studies B~~~~~~boron has a very high neutron capture cross- [11-121. The source molecule gas closo-1,2- section (400 barns for llB and 4000 barns for 1°B), the dicarbadecaborane (ortho-carborane) was used to grow the semiconductor devices according to the present invention boron carbide while nickelocene (Ni(CsHs)z) was used to 30 may be advantageously employed as solid state neutron intmduce nickel into the growing film. Other dopants can be detectors. By inclusion, enrichment, or replacement of the introduced using other metallocenes, including, for example, natural isotope abundance of boron with the 10~isotope, chromium (chromocene), manganese (manganocene), iron neutron capture cross-section is improved and the neutron (ferrocene), cobalt (cobaltocene), and ruthenium detector device made more effective. Multiple detectors may (ruthenocene). Like organometallic compounds can be used 35 be formed into an array, or, many layers of the boronlboron to extend the range of dopants even further. carbide diodes in accordance with the present invention may In still further embodiments, the boron carbide layer is be stacked to provide a neutron calorimeter to measure both doped with phosphorous. In one embodiment, phosphorous neutrons and their energy. Neutron detectors employing the doped boron carbon alloy films were made by chemical 40 boronlboron carbide semiconductor devices in accordance vapor deposition from a single source compound, dimeric with the present invention may be used for monitoring the chloro-phospha(II1)carborane ((C2BloHlo)2(PC1)2)and the operation of nuclear reactors, monitoring spent nuclear fuel, resulting phosphorous doped B5C materials exhibited monitoring weapons storage, and for neutron scattering. increases in the band gap from 0.9 eV to 2.6 eV. Other The boronlboron carbide semiconductor devices accord- methods of ~hos~horousinclusion may also be employed, 45 ing to the present invention also find utility as sensors for hot and will also increase the band gap substantially. oil wells. Currently, MOS device packages are used to Typical boron carbidein-type silicon heterojunctions have measure the temperature of hot oil wells. At present, 82% of been routinely formed by this technique [ll-141 as seen in well logging equipment applications require operation up to FIG. 4a. With inclusion of nickelocene as an additional 200" C., with the remaining 18% requiring operation up to source gas, nickel was included in the growing boron so 260' C. Newer markets in deeper and thus hotter wells carbide thin film. The presence of nickel at high doping requires operation up to 400' C. The boronlboron carbide levels was established by Auger electron spectroscopy semiconductor devices according to this teaching have been employing a cylindrical mirror analyzer (Perkin Elmer found to operate reliably at temperatures up to 560' C., thus double pass CMA) as the electron energy analyzer. Several making them well-suited for use in such applications. different partial pressures of nickelocene were employed. 55 The boronlboron carbide semiconductor devices accord- LOWrelative partial pressures of nickelocene to orthocarbo- ing to the present invention may also be used in aerospace rane during film growth (~0.1)resulted in the heterojunction applications. The harsh environment of the engine requires diode shown in FIG. 4b while higher partial pressure ratios current electronics to operate in temperatures up to 2.50' C. (about 9) resulted in the heterojunction diode shown in FIG. Recent applications of high temperature electronics include 4c. 60 Sic photodiodes as flame indication sensors, but all of the The consequence of inclusion of nickelocene with ortho- devices require external cooling jackets to operate. Elimi- carborane as a source gas, the normally p-type boron nation of these cooling jackets would lead to decreases in the carbide, relative to the n-type silicon, results in the forma- size and weight of sensor packages and decreased engine tion of rectifying diodes with reverse bias. Thus the nickel emissions and pollutants. doped boron carbide heterojunction diodes appears n-type 65 The boronlboron carbide semiconductor devices may also relative to the lightly doped n-type silicon substrate. This is be used in "smart-skin" applications. Since the semicon- consistent with the fabrication of n-p heterojunctions diodes ducting material of the present invention may be deposited US 6,600,177 B2 7 8 directly on titanium, such materials can be used in the [12] S. Lee and P. A. Dowben, J. Appl. Phys. A58, 223 transmit and receive circuits of radar, and arrays of such (1994); S. Lee, T. Ton, D. Zych and P. A. Dowben, Matev. circuits can be "painted" directly on an airframe assembly Res. Soc. Symp. Proc. 283, 483 (1993). for use in radar. The semiconductor devices prepared in [13] Seong-Don Hwang, Dongjin Byun, N. J. Ianno, P. A. accordance with the present invention are robust and operate 5 Dowben, and H. R. Kim, Appl. Phys. Lett 68(11), 1495 at high temperatures and thus are well suited to high power (1996). applications of this type. [14] D. Byun, B. R. Spady, N. J. Ianno, and P. A. Dowben, The boronboron carbide devices in accordance with this Nanostructured Mat. 5, 465 (1995). teaching may also be used as sensors in automobile engines. D. Byun, S. -D. Hwang, P. A. Dowben, F. K. Perkins, Sensors in car engines currently do not exceed 100" C., lo F. Filips and N. J. Ianno, Appl. Phys. Lett. 64, 1968 however, direct control of the engine, transmission, antilock braking system, and manifold absolute pressure is expected [I6] D. N. Mcllroy, Jiandi P. A. Dowben, P. Xu and to increase the temperature requirements. D. Heskett, Surface Science 328, 47 (1995). [17] D. N. McIlroy, J. Zhang, P. A. Dowben and D. Heskett, The boronboron carbide devices in accordance with the Mat, Sci, Eng, (1996), in press, present may be used as "thrOw-awa~" 1s [18] L, F, Warren, and M, F, Hawthorne, J, Am, Chem, Sot, in forms used in the fabrication of steel parts. The problem 90, 4823 (1990); L, F, Warren, and M, F, Hawthorne, J, with steel form sensors is that molten steel is very corrosive A,, them, sot, 92,1157 (1970); M, F, ~~~~h~~~~,D, C, and as a result very few sensors work in contact with molten young, T, D, ~~d~~~~,D, V, H~~~,R, L, pillings, A, D, steel. Such sensors are used to make sure the molten steel pitg, M, ~~i~tj~~,L, F, warrenand p, A, wegner, J, A~, fills all Parts of the form, in particular Parts where vapor 20 Chem. Soc. 90, 879 (1968); K. Y. Callahan and M. F. tends to get trapped as the molten steel is poured into the Hawthorne, Adv. Organometallic Chem. 14, 145 (1976). form. [19] K. Widder, D. Berner, A. Zibold, H. P. Geserich, M. The description above should not be construed as limiting Knupper, M. Kielwein, M. Buchgeister and J. Fink, the scope of the invention, but as merely providing illustra- Europhys. Lett. 30, 55 (1995); R. J. Cava, B. Batlogg, J. tions to some of the presently preferred embodiments of this 2s J. Krajewski, W. F. Peck, T. Siegrist, R. M. Fleming, S. invention. In light of the above description and examples, Carter, H. Takagi, R. J. Felder, R. B. van Dover and L. W. various other modifications and variations will now become Rupp, Physica C, 226, 170 (1994); T. Siegrist, H. W. apparent to those skilled in the art without departing from Zandbergen, R J. Cava, J. J. Krajewski and W. F. Peck, the spirit and scope of the present invention as defined by the Nature 367, 254 (1994); R. J. Cava, H. Takagi, H. W. appended claims. Accordingly, the scope of the invention 30 Zandbergen, J. J. Krajewski, W. F. Peck, T. Siegrist, B. should be determined solely by the appended claims and Batlogg, R. B. van Dover, R. J. Felder, K. Mizuhashi, J. their legal equivalents. 0. Lee, H. Eisaki and S. Uchida, Nature 367,252 (1994); All references cited herein are expressly incorporated by R. Nagarajan, C. Mazumdar, Z. Hossain, S. K. Dhar, K. reference in their entireties. V. Gopalakrishnan, L. C. Gupta, C. Godart, B. D. Padalia, 35 and R. Vijayaraghavan, Phys. Rev. Lett. 72, 274 (1994). REFERENCES [20] N. Kobayashi, Y. Kumashiro, P. Revesz, J. Li, and J. W. [I] H. E. Robson, Ph.D. dissertation, University of Kansas Mayer, Matev. Res. Soc. Symp. Proc. 162, 595 (1990). (1959). [21] N. Kobayashi, Y. Kumashiro, P. Revesz, J. Li, and J. W. [2] S. Lee and P. A. Dowben, J. Appl. Phys. A58,223 (1994). Mayer, Appl. Phys. Lett. 54, 1914 (1989). [3] S. Lee, J. Mazurowski, G. Ramseyer and P. A. Dowben, 40 [22] Y.-G. Kim, D. Byun, C. Hutchings, P. A. Dowben, H. J. Appl. Phys. 72, 4925 (1992). Hejasi, and K. Schroeder, J. Appl Phys. 70, 6062 (1991); [4] J. C. Lund, F. Olschner, F. Ahmed and K. S. Shah, Mat. G. T. Stauf, and P. A. Dowben, Thin Solid Films 156, L31 Sci. SOC.Symp. Proc. 162, 601 (1990). (1988); G. T. Stauf, D. C. Driscoll, P. A. Dowben, S. [5] Dongjin Byun, S. Hwang, P. A. Dowben, F. K. Perkins, Barfuss, and M. Grade, ThinSolid Films, 153,421 (1987). F. Filips and N. J. Ianno, Appl. Phys. Lett. 64, 1968 45 [23] N. M. Boag and P. A. Dowben, Metallized Plastics 4: (1994). Fundamental andAppliedAspects, Edited by K. L. Mittal, [6] Dongjin Byun, B. R. Spady, N. J. Ianno and P. A. Plenum Press, New York (1996); D. Zych, A. Patwa, S. S. Dowben, Nanostructured Materials 5, 465 (1995). Kher, J. T. Spencer, J. Kushneir,A. J. Goodby, N. M. Boag [7] J. Mazurowski, S. Baral-Tosh, G. Ramseyer, J. T. and P. A. Dowben, J. Appl. Phys. 76, 3684 (1994). Spencer, Y. -G. Kim and P. A. Dowben, in Plasma so [24] T. P. Brody, J. ApplPhys. 38,2384 (1967); E. 0. Kane, Processing and Synthesis of Materials, MRS Symposium J. Appl. Phys. 32, 83 (1961); E. 0. Kane, Phys. Chem. Proceedings, edited by D. Apelian and J. Szekely (MRS, Solids 2, 181 (1960); A. G. Chynoweth, W. L. Feldmann Pittsburgh, Pa. 1991), vo1.190, p.101; J. Mazurowski, S. and R A. Logan, Phys. Rev 121,684 (1961); R A. Logan Lee, G. Ramseyer and P. A. Dowben, in Wide Band Gap and A. G. Chynoweth, Phys. Rev. 131, 89 (1963), R. S. Semiconductors MRS Symposium Proceedings, edited by ss Claassen, J. Appl. Phys. 32, 2372 (1961); A. S. Epstein T. D. Moustakas, J. I. Pankove and Y. Hamakawa (MRS, and J. F. Caldwell, J. Appl. Phys. 35, 3050 (1964); D. Pittsburgh, Pa. 1992), vo1.242, p.637. Meyerhofer, G. A. Brown and H. S. Sommers Jr., Phys. [8] F. K. Perkins, R. A. Rosenberg, S. Lee and P. A. Dowben, Rev. 126, 1329 (1962); R. M. Minton, and R. Glicksman, J. Appl. Phys. 69, 4103 (1991). Solid State Electron 7, 491 (1964); J. Karlovsky, Solid [9] R. A. Rosenberg, F. K. Perkins, D. C. Mancini, G. R. 60 State Electron 10, 1109 (1967). Harp, B. F. Tonner, S. Lee and P. A. Dowben,Appl. Phys. [25] H. Werheit, U. Kuhlmann, M. Laux and T. Lundstrgm, Lett. 58, 607 (1991). Phys. Stat. Sol. 179, 489 (1993). [lo] A. P. Hitchcock, A. T. Wen, S. Lee, J. A. Glass, J. T. [26] H. Werheit, M. Laux, and U. Kuhlmann,Phys. Stat. Sol. Spencer and P. A. Dowben, J. Phys. Chem. 97, 8171 176, 415 (1993). (1993). 65 [27] Seong-Don Hwang, N. B. Remmes, P. A. Dowben, and [ll] S. Lee, J. Mazurowski, G. Ramseyer, and P. A. Dowben, D. N. McIlroy, J. Vacuum Sci. & Tech. B 14(4), 2957, J. Appl. Phys., 72, 4925(1992). 1996. US 6,600,177 B2 9 10 What is claimed is: 9. A semiconductor device comprising a first layer of 1. A semiconductor device comprising a first layer of substrate material, said substrate material comprising a substrate material, said substrate material comprising a metal or semiconductor material; a second layer comprising metal or semiconductor material; and a second layer corn- elemental boron deposited on said first layer; a third layer prising elemental boron deposited on said first layer, 5 comprising boron carbide deposited on said second layer; wherein said second layer is doped with a dopant including and a fourth layer comprising boron carbide doped with a an organometallic. dopant including an organometallic. 2, A semiconductor device according to claim wherein 10. Asemiconductor device according to claim 9, wherein said organometallic compound is a metallocene. said organometallic compound is a metallocene. 11. A semiconductor device accord to claim 9, wherein 3. Asemiconductor device accord to claim 1, wherein said 10 said organometallic compound is selected from the group organometallic compound is selected from the group con- consisting of nickelocene, nickel carbonyl, chromocene, sisting of nickelocene, nickel carbonyl, chromocene, manganocene, ferrocene, cobaltocene, and ruthenocene. manganocene, ferrocene, cobaltocene, and ruthenocene. 12. Asemiconductor device according to claim 9, wherein 4. A semiconductor device according to claim 1, wherein said metal includes at least one of nickel, chromium, said metal includes at least one of nickel, chromium, IS manganese, iron, cobalt, and ruthenium. manganese, iron, cobalt, and ruthenium. 13. A semiconductor device comprising a first layer of 5. A semiconductor device comprising a first layer of substrate material, said substrate material comprising a substrate material, said substrate material comprising a metal or semiconductor material; a second layer comprising metal or semiconductor material; and a second layer com- elemental boron deposited on said first layer; a third layer prising elemental boron deposited on said first layer, 20 comprising boron carbide deposited on said second layer; wherein said second layer is doped with a dopant selected and a fourth layer comprising boron carbide doped with a from the group consisting of phosphorous, nickel, dopant selected from the group consisting of phosphorous, chromium, manganese, iron, cobalt, and ruthenium. nickel, chromium, manganese, iron, cobalt, and ruthenium. 6. A semiconductor device according to claim 5, wherein 14. A semiconductor device according to claim 13, said dopant is phosphorous. 25 wherein said dopant is phosphorous. 7. A semiconductor device according to claim 5, wherein 15. A semiconductor device according to claim 13, said dopant is selected from the group consisting of nickel, wherein said dopant is selected from the group consisting of chromium, manganese, iron, cobalt, and ruthenium. nickel, chromium, manganese, iron, cobalt, and ruthenium. 8. A semiconductor device according to claim 5, wherein said dopant is nickel. *****